A whiles back I made some hollow promises about justifying my love of for Halo 3's multiplayer. And while honoring my pledges runs contrary to my principles, I do want to extol the game's many excellences. I've been playing the game a bit on and off since I wrote that post and now that it's lost the near-shamanic command over my soul that it once had, I feel like I can discuss it in terms of appreciation rather than addiction. I should add the few caveats: I am not an expert on shooter games. Prior to Halo 3, my only experience with multiplayer shooters came from a couple rounds of 56K dial-up Doom 2 with my friend Erik. (I lost. Badly.) So don't take this as a declaration of Halo's superiority to all other shooters. Also, I am not terribly good at Halo 3.
For me, the real bedrock of Halo 3's appeal is the controls. I think the central design problem in making a shooter for the console is getting the feel of the controls right, and to my mind Bungie's main accomplishment is communicating a real sense of movement and physicality through an Xbox gamepad. A lot of shooters can make you feel like you're just a viewpoint floating in space, and Halo 3 has all these small touches that give your character a sense of substance and weight as she moves through the world-- the way the perspective shudders subtly to suggest the Spartan's gait, the way you hang in the air at the apex of a jump. Each of the weapons also has a really distinctive feel-- even if you couldn't see or hear the TV, you could tell an assault rifle from a battle rifle from a shotgun in a second just by holding the controller in your hands as you fire them. I've heard that Japanese developers, who have traditionally held American game development in low esteem, have a great deal of respect for Bungie, and you can understand why. Bungie has done for shooters what Nintendo did for platformers: they've turned the visceral joys control and motion into the centerpiece of the game.
Maybe a point of comparison will help clarify. I finally played though the Half-Life 2 saga last fall when I picked up the Orange Box (which is, officially, the greatest game bargain of all-time), and that game also has really visceral and thrilling combat. But in Half-Life, all the physicality comes from the the realistic behavior of the enemies and objects in the world: I'll never forget the way a Combine solider crumples when you hit him at close range with a shotgun. The physics model of Half-Life 2 is unparalleled when it comes to conveying realistic explosions, but when it comes to control I never quite shook the feeling that I was just gliding over pieces of the environment rather than walking on them. Unlike Halo, I never felt that I was holding a person in my hands.
So, on top of its excellent controls I feel the real strength of Halo lies in the variety and refinement of its combat mechanics. The driving idea behind Halo's combat is to create engagements at three distinct registers: long, medium, and short-range. Succeeding at each of these three distances requires the mastery of a different set of weapons and tactics; lobbing your grenades well is one of the essential skills in the game, and using them effectively is a different proposition at each of these three distances. Bungie did a great job of balancing the various weapons such that there are a variety of plausible weapons and strategies at each register. For me, honing my skills with the battle rifle until I was good enough to have a competent long-distance game kept me engrossed in the game for hours and hours. (My short game is pretty subpar, and I still can't snipe to save my life.) Because the range of distances and range of weapons, there's just a lot to learn and perfect and refine as you play.
While certain maps favor different types of combat, the map design on the whole uses its geography in order to encourage combat at a variety of distances, so there is always an opportunity to work on different parts of your game regardless of the map you end up on. Despite my uneven mastery of the various weapons and skills I always felt like I could be effective on any map if I strategized well enough, and this is a testament to the quality of the map design as a whole.
I'm not blind to Halo's faults. Unless you happen to hate all ethnic, religious, and sexual minorities, the Xbox Live experience can be pretty abysmal at times. Because of this I've never really gotten a the sort of collaborative team-play experience out of Halo that you can get from Team Fortress on the PC . Maybe I just need some friends who play on Xbox live who are not sociopaths or 14-year olds. There's also not a lot of variety to the game modes, and so far as my experience goes you have to squeeze all the fun you can out of playing Slayer over and over again. But for me, that well's never run dry.